(1. 東北大學 材料與冶金學院，沈陽 110819；
2. 中國科學院 過程工程研究所，北京 100190；
3. 河北省石油化工設計院 蘇州分院，蘇州 215011)
摘 要: 采用激光濁度法對亞熔鹽法粉煤灰提鋁清潔工藝中硫酸鈉在亞熔鹽介質(zhì)中的過飽和性進行了研究。結果表明：對亞熔鹽介質(zhì)進行真空蒸發(fā)時，其中的硫酸鈉達到平衡濃度時即從體系中結晶析出，表明硫酸鈉在亞熔鹽介質(zhì)中幾乎無過飽和性。此外，雜質(zhì)二氧化硅與碳酸鈉對硫酸鈉在鋁酸鈉溶液中的過飽和性具有一定影響，二氧化硅雜質(zhì)會使硫酸鈉析晶點堿濃度提高到20 g/L左右；碳酸鈉會使硫酸鈉析晶點堿濃度降低至15 g/L左右。同時，對析出晶體的物相分析表明：雜質(zhì)二氧化硅的存在會使析出晶體向鈉硅渣轉變，而雜質(zhì)碳酸鈉的存在會使析出晶體向碳鈉礬復鹽轉變。
關鍵字: 硫酸鈉；亞熔鹽；過飽和性；粉煤灰
（1. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China;
2. Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
3. Suzhou Branch, Hebei Petrochemical Design Institute, Suzhou 215011, China）
Abstract:The supersaturation of sodium sulfate in sub-molten salt during the process of extracting alumina from fly ash by sub-molten method was investigated by laser-turbidity method. The results show that during the process of vaporization, when the concentration of sodium sulfate in sub-molten salt exceeds the limit of solubility, it will be deposited out in solid form. There is not an obvious supersaturation phenomenon for the sodium sulfate in vaporization process. The impurities of silica and sodium carbonate have certain influences on the supersaturation of sodium sulfate in sub-molten salt. The silicon impurity increases the crystallization alkali concentration of sodium sulfate by 20 g/L. On the other hand, the sodium carbonate decreases the crystallization alkali concentration of sodium sulfate by 15 g/L. Meanwhile, the results of X ray diffraction analyses indicates that the SiO2 changes the crystal from crystalline precipitated to sodium-silicon residue，while the addition of Na2CO3 changes crystals to the burkeite.
Key words: sodium sulfate; sub-molten salt; desulfurization; fly ash
